I'd skip the P3 module.. I love the platform but that really only makes sense if you're also going to invest in a P3.. and they ain't cheap You've got a lot of solid ideas down -- if you really want to maximize what you incorporate than I agree that a wide body is the way to go... that said, you're spending THAT much more time getting the layout worked out, more $$ on mechs & electronics & parts probably, and in the end a slower game. Guess it depends how much time you expect to put into this and if you like wide body machine play or want something faster.. Also with wide body there's less donor cab's available so you might be looking most definitely at buying new (I think virtualpin does wide bodies?) or building yourself.
You've got a lot of elements and wishes for a first homebrew. Take whatever time you think this will take and multiply by like 3 (at least) lol. Same with $$.
Sounds like you're ready to start building a foamcore though. Decide on wide or standard and go for it! Cut a blank piece of ply and start hot gluing foamcore and cardboard, go nuts! Even better if you can decide on a boardset first, and get the lower 3rd in so you have working flippers and slings to shoot balls around while you test things out and move things.
As mentioned - shots are really limited by that ball width factor + whatever protective element or target that sandwiches them.. so realistically on a standard game with a fan layout I think most get between 6-8 shots if I remember right? Upper playfield is slightly easier than the lower.. the windows for lower playfields are a bit of a pain to deal with. certainly doable though.. just not sure how fun they are for the effort.
Love the starmap in the backglass area with spinning discs. I'd ditch the apron LCD and just track relics with inserts. Once you get 1/2 thru, you may find yourself ditching some overly ambitious ideas like the ropes and apron LCD.
Have you seen the "Escape from the lost world" pin? You should check it out.. I could see something similar on yours with an upper playfield shot thru a backboard.. and if you had a bridge like escape.. that is a FUN shot when you make it! Does take up some space though.
Look into a 3d printer if you don't already have one. It's nice to have spare mechs on hand too.. I'd make a big order from pinball life and pick up a target, sling stuff, 2 full flipper setups, maybe a rubber kit, some posts, and a few things you'll likely use but don't know where they go yet. Having them as reference for size is really nice.. then you can mock up accurately with foamcore.
Most importantly - don't forget to document your journey here! Love following Homebrew threads!